Interpretive Summary: Rice (Oryza sativa L.) is a staple food for approximately one half of the world’s population. Studies have reported associations between whole grain rice consumption and anti-carcinogenic activity and blood-glucose lowering ability. These health-beneficial properties are largely contributed by several antioxidant fractions in the bran of unmilled rice. The demand for rice bran and its oil is increasing because consumers are learning about its potential health effects. In addition, the lipid content and types of fatty acid in bran are potential breeding targets for rice. Greater lipid content would increase the value of rice bran destined for oil extraction, while a high content of saturated fatty acid, such as palmitic acid, would increase oil stability during frying. The Oryza genus is small, including only 23 species. The diversity of ecological zones in which these species have been found is remarkable. This diversity may not be restricted to ecological characteristics, but may extend to end-use quality properties. This study investigated the potential for using Oryza species as a genetic source for enhancing the lipid quality and antioxidant contents of rice bran. The level of palmitic acid in the Oryza species was higher than that of cultivated rice. The Oryza species also contained high levels of the gamma-oryzanol and phenolic fractions compared to cultivated rice. The results suggest that there is potential for using Oryza species to enhance the levels of palmitic acid, gamma-oryzanol and phenolic content in the bran of cultivated rice.

Technical Abstract:
The genus Oryza has given rise to rice (Oryza sativa L.), a major source of food for much of the human population. The Oryza genus is small, including only 23 species, but it is remarkably diverse in terms of its ecological adaptation. This diversity may not only be restricted to ecological characteristics but also to kernel quality characteristics. This study was undertaken to evaluate Oryza species as a gene pool for improving the properties of rice bran for human consumption. Several accessions of thirteen Oryza species were grown in a greenhouse, along with eight rice (Oryza sativa L.) accessions displaying low and high bran oil content as well as low and high palmitic acid content. The total lipid content of the Oryza species was within the range found for Oryza sativa accessions. However, the level of palmitic acid in the Oryza species was as high as that reported for sunflower high-palmitic acid mutants. The Oryza species also contained higher levels of the gamma-oryzanol and phenolic fractions compared to cultivated rice. Low phenotypic correlations between lipid, palmitic acid and gamma-oryzanol indicate that these fractions in cultivated rice could be increased simultaneously using several of the Oryza species accessions identified in this study. A cultivar with enhanced levels of these fractions would be suitable for use in the production of high gamma-oryzanol margarine, shortening and frying oils.